Spinal plate system and related methods

ABSTRACT

Implementations of devices for use in cervical spinal operations. Implementations may include a template including a central hole therethrough and two or more screw holes therethrough. The central hole may be configured to be inserted over a handle of a trial. The template may be configured to place a first of the two or more screw holes over a rostral vertebra and to place a second of the two or more screw holes over a caudal vertebra. Implementations may also include a template including a central hole therethrough and two or more screw holes therethrough. The central hole may be configured to couple over an inserter. The template may be configured to place a first of the two or more screw holes over a rostral vertebra and to place a second of the two or more screw holes over a caudal vertebra.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/493,183, titled “Spinal Plate System and RelatedMethods,” to Luis M. Tumialán, filed Sep. 22, 2014, which is acontinuation application of U.S. patent application Ser. No. 13/525,313,titled “Spinal Plate System and Related Methods,” to Luis M. Tumialán,filed Jun. 16, 2012, which claims the benefit of the filing date of U.S.Provisional Patent Application 61/497,528, entitled “Cervical PlateSystem and Related Methods” to Luis M. Tumialán which was filed on Jun.16, 2011, and also claims the benefit of the filing date of U.S.Provisional Patent Application 61/511,639 entitled “Cervical PlateSystem and Related Methods” to Luis M. Tumialán which was filed on Jul.26, 2011, the disclosures of which are each hereby incorporated entirelyherein by reference.

BACKGROUND 1. Technical Field

Aspects of this document relate generally to spinal plate systems, suchas those used in spinal vertebral fusion operations and procedures.

2. Background Art

Cervical spinal vertebral fusion surgeries generally involve the stepsof surgical exposure of two or more vertebrae, removal of the discbetween the vertebrae (discectomy and decompression), placement of aninterbody graft between the vertebrae to maintain a desired spacingbetween the vertebrae (the size of the interbody graft being determinedusing a metal spacer or trial inserted between the vertebrae), and thescrewing of a metal plate to the two or more vertebrae to hold them andthe graft in place while physical fusion of the bone of the vertebraetakes place.

SUMMARY

Implementations of cervical spinal surgical systems may utilizeimplementations of devices for use in cervical spinal surgeries.Implementations may include a template including a central holetherethrough and two or more screw holes therethrough. The central holemay be configured to be inserted over a handle of a trial. The templatemay be configured to place a first of the two or more screw holes over arostral vertebra and to place a second of the two or more screw holesover a caudal vertebra.

Implementations of devices for use in cervical spinal operations mayinclude one, all, or any of the following:

The two or more screw holes may be centering holes configured to permita user to drill two or more centering holes into one or more vertebraefor two or more centering pins for a plate.

The two or more screw holes may be pilot screw holes configured topermit a user to drill two or more pilot holes into one or morevertebrae for two or more plate screws.

The template may include only two pilot screw holes and a first of theonly two pilot screw holes may be located on a first side of a midlineand a second of the only two pilot screw holes may be located along asecond side of the midline and the only two pilot screw holes may alsobe located along a diagonal line extending through each of the only twopilot screw holes and the central hole of the template.

The template may include only four pilot screw holes each of which areconfigured to align with the position of a corresponding one of fourplate screw holes comprised in a plate.

The template may include a sleeve coupled to the template at the centralhole where the sleeve is oriented substantially perpendicularly to thetemplate and extends around the central hole.

A plate may be included which may include two or more centering slotstherethrough configured to permit the plate to move rostrally andcaudally when the plate is placed over the or more centering screwsscrewed into the one or more vertebrae.

The template may include a first portion and a second portion where thefirst portion includes the two or more screw holes therethrough and acentering hole and the second portion includes a centering hole and asecond center hole.

Implementations of cervical spinal surgical systems may utilizeimplementations of devices for use in cervical spinal operations.Implementations may include a template including a central holetherethrough and two or more screw holes therethrough. The central holemay be configured to couple over an inserter. The template may beconfigured to place a first of the two or more screw holes over arostral vertebra and to place a second of the two or more screw holesover a caudal vertebra.

Implementations of devices for use in cervical spinal operations mayinclude one, all, or any of the following:

The two or more screw holes may be centering holes configured to permita user to drill two or more centering holes into one or more vertebraefor two or more centering pins for a plate.

The two or more screw holes may be pilot screw holes configured topermit a user to drill two or more pilot screw holes into one or morevertebrae for two or more plate screws.

The template may include only two pilot screw holes and a first of theonly two pilot screw holes may be located on a first side of a midlineand a second of the only two pilot screw holes may be located on asecond side of the midline and the only two pilot screw holes may bealso located along a diagonal extending through each of the only twopilot screw holes and the central hole of the template.

The template may include only four pilot screw holes, each of which areconfigured to align with the position of a corresponding one of fourplate screw holes included in a plate.

A coupling member may be included configured to couple to the insertedcoupled to a graft and configured to secure a plate to the graft throughcoupling to the inserter.

The coupling member may further include a center piece coupled to twoside blocks through a dovetail joint in each of the two side blocks.

The template may include a first portion and a second portion where thefirst portion includes the two or more screw holes therethrough and acentering hole and the second portion includes a centering hole and asecond center hole.

The template may further include a sleeve coupled to the template at thecentral hole where the sleeve is oriented substantially perpendicularlyto the template and extends around the central hole.

The template may include two prongs configured to engage with templateopenings in the graft and the inserter may include a flange at an end ofthe inserter opposing the graft where the flange is configured toslidably engage with an end of the sleeve as the inserter is coupledwith the graft and to secure the template to the graft through theflange when the inserter is fully coupled with the graft.

Implementations of cervical spinal surgical systems may utilizeimplementations of a device for use in a cervical spinal operation.Implementations of the device may include a trial having a handle wheretwo opposing edges of the trial each include a slope configured tocorrespond with a slope of an uncal vertebral joint of a vertebra.

Implementations of devices for use in cervical spinal operations mayinclude one, all, or any of the following:

The trial may be configured to automatically center the handle over themidline position of two vertebrae through the slope included in each ofthe two opposing edges of the trial.

Implementations of cervical spinal surgical systems may utilizeimplementations of a device for use in a cervical spinal operation.Implementations of the device may include an interbody graft having twoopposing edges which each include a slope configured to correspond witha slope of an uncal vertebral joint of a vertebra.

The foregoing and other aspects, features, and advantages will beapparent to those artisans of ordinary skill in the art from theDESCRIPTION and DRAWINGS, and from the CLAIMS.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations will hereinafter be described in conjunction with theappended drawings, where like designations denote like elements, and:

FIG. 1 is a perspective view of a trial;

FIG. 2A is a perspective view of a first implementation of a template;

FIG. 2B is a perspective view of a second implementation of a templatehaving a sleeve;

FIG. 2C is view of a template implementation being inserted over ahandle of a trial;

FIG. 3 is a perspective view of a template inserted over the handle of atrial inserted between two vertebrae;

FIG. 4 is an intraoperative lateral fluoroscopic image illustrating a 6mm lordotic cervical trial in position;

FIG. 5 is a perspective view of a graft inserted between two vertebraeillustrating the position of two centering holes;

FIG. 6A is an exploded view of a plate adjacent to two centering screwsinserted into two vertebrae;

FIG. 6B is a perspective view of a plate coupled over the two centeringscrews through two centering slots;

FIG. 7A is a perspective view of a third implementation of a templateinserted over a trial handle;

FIG. 7B is a perspective view of a fourth implementation of a templateinserted over a trial handle;

FIG. 8A is a perspective view of a first portion of a fifthimplementation of a template;

FIG. 8B is a perspective view of a second portion of a fifthimplementation of a template;

FIG. 8C is a perspective view of a first section of a template insertedover a trial handle after centering holes have been drilled using thesecond section;

FIG. 9A is an exploded perspective view of a sixth implementation of atemplate;

FIG. 9B is a perspective view of the sixth implementation illustrated inFIG. 9A fully coupled to a graft;

FIG. 10 is a perspective view of a seventh implementation of a templatecoupled to a graft;

FIG. 11 is a perspective see through view of a plate coupled to a graftthrough a coupling member;

FIG. 12 is a detail perspective view of an implementation of a couplingmember;

FIG. 13 is a perspective view of the implementation of a coupling memberof FIG. 12 coupled over a plate and holding the plate against a graft;

FIG. 14 is a front view of a first implementation of a graft insertedbetween two vertebrae;

FIG. 15A is an exploded perspective view of an implementation of aneighth implementation of a template adjacent to a graft implementationlike that illustrated in FIG. 14;

FIG. 15B is a top view of the eighth template implementation illustratedin FIG. 15A;

FIG. 16A is a perspective view of the eighth template implementationadjacent to the graft implementation illustrated in FIG. 14;

FIG. 16B is a perspective view of an inserter inserted into a sleeve ofthe eighth template implementation and inserted into the graft;

FIG. 16C is a perspective view of the inserter fully coupled with thegraft and securing the template to the graft through a flange on theinserter;

FIG. 17 is a perspective view of an implementation of a trial;

FIG. 18 is a front perspective view of an implementation of a graft;

FIG. 19 is an CT scan of a plate screwed to two vertebrae illustratingthe position of a graft;

FIG. 20 is a lateral intraoperative fluoroscopic image of a plateshowing a first plate holding pin;

FIG. 21 is a lateral intraoperative fluoroscopic image of a plateshowing a first and second plate holding pin;

FIG. 22 is a lateral intraoperative fluoroscopic image of a plateshowing a plate screw;

FIG. 23 is a post operative AP x-ray image indicating the midlinepositioning of the plate on the cervical vertebrae;

FIG. 24 is a front view of another implementation of a template.

DESCRIPTION

This disclosure, its aspects and implementations, are not limited to thespecific components or assembly procedures disclosed herein. Manyadditional components and assembly procedures known in the artconsistent with the intended spinal plate systems and/or assemblyprocedures for a spinal plate system will become apparent for use withparticular implementations from this disclosure. Accordingly, forexample, although particular implementations are disclosed, suchimplementations and implementing components may comprise any shape,size, style, type, model, version, measurement, concentration, material,quantity, and/or the like as is known in the art for such spinal platesystems and implementing components, consistent with the intendedoperation.

Implementations of spinal plate systems and related methods may beemployed in a wide variety of cervical spinal procedures, includingspinal fusion operations and arthroplasty (artificial disc) operations(for simplicity's sake, referred to herein as “spinal surgicalsystems”). These may include, by non-limiting example, anterior cervicaldiscectomy and fusion (ACDF) and artificial disc placement. In the caseof an ACDF operation, such a fusion operation involves the steps ofsurgical exposure of two or more cervical vertebrae, removal of the discbetween two or more cervical vertebrae (discectomy and decompression),placement of an interbody graft between the cervical vertebrae tomaintain a desired spacing between the vertebrae (the size of theinterbody graft being determined using a metal spacer or trial insertedbetween the vertebrae), and the screwing of a cervical plate to the twoor more cervical vertebrae to hold them and the graft in place while theactual fusion of the bone of the two vertebrae takes place. In manysituations, the plate is secured to the anterior aspect of the vertebralbody adjacent to the throat with four screws which are located in fourholes in the plate. Fluoroscopic imaging is employed during and afterthe operation and may be taken in the anteroposterior direction (AP, orfrom front to back, from the throat through the back of the neck) and/orin the lateral direction (from the side of the neck) to determine wherethe plate and screws are placed relative to the bone of the vertebraeafter the plate has been screwed over the bone. Important considerationsin determining the success of ACDF surgery may be the orthogonality ofthe plate, the alignment of the plate with the midline of the vertebraeto which it has been screwed, and whether a plate with the smallestpossible length was employed to complete the fusion. It is believed thatplates aligned with the midline and which are as short as possibleresult in the best patient outcomes over time. Oversized plates havebeen associated with an increased incidence of adjacent segmentdegeneration, where the vertebral level above the plate degeneratesbecause the presence of the plate acts to erode the disc space. Cervicalspinal surgical systems disclosed in this document may simultaneouslyalign the plate over the midline, achieve a plate position orthogonalwith the midline while permitting the use of the shortest plate possiblein a given surgical procedure.

Cervical spinal surgeries can involve two or more vertebrae. In ACDF andother spinal fusion surgeries, fusions that involve two vertebrae arereferred to as single level surgeries, while surgeries that involvethree or more vertebrae are referred to as two (or three, etc.) levelsurgeries. In this document, various implementations of cervical spinalsurgical systems that can be utilized in single level surgeries will bediscussed, along with implementations that may be utilized in two levelsurgeries.

In this document, the steps of an ACDF operation are used as an exampleof a type of spinal fusion surgery that may utilize implementations ofcervical spinal surgical systems disclosed herein. However, the use ofthe ACDF surgical procedure is purely for the exemplary purposes of thisdisclosure and does not limit the application of the cervical spinalsurgical system implementations to only ACDF operations. Those ofordinary skill in the art will readily be able to utilize the principlesdisclosed herein to apply the various cervical spinal surgical systemimplementations in many other cervical spinal procedures.

In a single level ACDF surgery, following surgical exposure of the twovertebrae, the midline of the two vertebrae is identified by the surgeonas the point between the uncal vertebral joints, or the midpoint on thewidth of vertebra between the beginning of the locations where thejoints begin to round or slope upward in preparation for engaging withthe vertebra above. Identification of the midline can take place eitherusing the longus coli muscles or during decompression using the uncalvertebral joints alone. To create a mark on the midline that can be usedthroughout the surgery, both the rostral and caudal vertebral bodies maybe bovied and tattooed using a marking pen. These marks providealignment points that are used later in the surgery.

Following discectomy and decompression, the surgeon determines what theproper spacing between the rostral and caudal vertebral bodies should bewhich determines the size of the interbody graft that should be placedbetween the vertebrae. The interbody graft works to aid in maintainingthe spacing between the two vertebrae during the fusion processfollowing surgery and can facilitate in the process of bone growthbetween the two vertebrae in some situations, depending upon thematerials which make up the graft. Referring to FIG. 1, the spacing isdetermined using various implementations of trials 2, each of which is ametal plate having a particular thickness with a metal handle 4attached. Trials come in sets of different sizes, and various sizedtrials are placed between the two vertebrae until a trial of the desiredthickness is identified. Once identified, it is maintained within thetwo vertebrae and firmly held between the two vertebrae. Because thewidth of the trial 2 is fairly close to the width of the vertebraebetween the slopes of the uncal joints, the handle 4 of the trialgenerally self-aligns with the midline marks on the two vertebrae.

Because the handle 4 of the trial generally remains self-aligned to themidline during the surgical procedure, implementations of templates likethose disclosed herein may utilize the handle of the trial as areference point in order to drill centering holes or pilot screw holesfor a plate.

Referring to FIG. 2A a first implementation of a template 6 isillustrated. As illustrated, the template 6 includes a center hole 8 andtwo screw holes 10, 12. In this first implementation, the two screwholes 10, 12 are centering holes which are used by the surgeon to drillcentering holes (centering screw holes) in the rostral and caudalvertebrae in preparation for the screwing of centering screws into theholes. The use of the centering screws will be discussed later in thisdocument. The center hole 8 is sized to enable the handle 4 of the trial2 to pass through it, allowing the surgeon to insert the template 6 overthe handle 4 of the trial 2 once the trial 2 has been put into position.Once in this position, the template 6 identifies the location of(places) the first centering screw hole 10 over the rostral vertebra andplaces the second centering screw hole over the caudal vertebra.Simultaneously, the first centering screw hole 10 and second centeringscrew hole 12 are aligned with the midpoint of both vertebrae since thehandle 4 of the trial 2 is self-aligned in the center of the spacebetween the two vertebrae.

Referring to FIG. 2B, a second implementation of a template 14 isillustrated. This template implementation includes a sleeve 16 that iscoupled to the template 14 at the center hole and extends outwardlyaround the center hole substantially perpendicularly relative to theplane formed by the template 14. While the sleeve 16 may be angledsubstantially perpendicularly, it may also be angled a desired number ofdegrees rostrally or caudally in order to accommodate a trial with anangled handle or the orientation needed for a specific cervical spinalprocedure. The sleeve 16 may serve to further stabilize the template 14during use while drilling centering screw holes. The sleeve may extend,by non-limiting example, a short distance, most of the length, amajority of the length, or the full length of the handle of the trial invarious implementations.

Referring to FIG. 2C, an implementation of a template 18 is illustratedbeing inserted over the handle 4 of a trial 2 like the one illustratedin FIG. 1. FIG. 3 illustrates the position of the template 18 relativeto the rostral and caudal vertebrae and illustrates the centeredposition of the centering screw holes through their alignment with thehandle 4.

Referring to FIG. 4, an intraoperative lateral fluoroscopic imageillustrating a 6 mm lordotic cervical trial inserted between twovertebrae is illustrated. In the image, the trial is located between twocentering screws that have been inserted into the rostral and caudalvertebrae located above and below the trial, respectively.

With the template inserted over the trial as illustrated in FIG. 3, thesurgeon will inspect the position of the centering screw holes (screwholes) holes on the rostral and caudal vertebrae to determine from theposition of the hole in the template if each hole is placed sufficientlyfar along the vertebra to ensure that adequate bone coverage exists tosupport a centering pin (centering screw). If the surgeon determinesthat the coverage is inadequate, the existing template can removed fromthe handle 4 and a differently sized template (longer or shorter) can beslid over the handle 4. In various implementations of cervical spinalsurgical systems the size of the template may correspond directly withthe size of the cervical plate that will be used (i.e., dimensions ofthe template may be the same as the dimensions of the plate, forexample, the length of the template and corresponding plate are thesame). For the exemplary purposes of this disclosure, the length of thetemplate may range between about 19 mm to about 27 mm in length, thoughcentering pin template sizes that are smaller or larger than these mayalso be used, depending upon the dimensions of the vertebrae involvedand the age and size of the patients. During the process of selectingthe proper template size, lateral fluoroscopic imaging may be employedto determine the location of the template that will provide adequatebone coverage for the screws and confirm and verify that the properlength has been selected. The use of a metal template means that thetemplate is visible using lateral fluoroscopic imaging. Further, sincethe template 18 is already centered over the midline through beingcoupled to the trial handle 4, the needed length of the cervical platemay be determined without the need to separately use AP fluoroscopicimaging to verify the plate length and/or position relative to themidline.

Once a desired template 18 has been determined, the centering holes aredrilled using the centering screw holes in the template 18, and thetemplate 18 and trial 4 are removed. Referring to FIG. 5, an interbodygraft 20 is then placed between the vertebrae. Implementations ofinterbody grafts that may be used in implementations of cervical spinalsurgical systems disclosed in this document may include any conventionalgraft type including those made of polyetheretherketone (PEEK), corticalcancellous grafts, other material types, and those that includeautograft or allograft materials within their interior to facilitate thefusion process. Due to the width of many conventional grafts, followingsurgery, the graft generally naturally automatically centers itself withrespect to the midline and can be used in imaging to establish areference point to see how centered the plate is following surgery. Oncethe interbody graft is placed, centering pins are screwed into thealready drilled centering holes 22, 24. FIG. 5 illustrates the placementof the graft 20 and the drilled centering holes 22, 24 after the trialand centering pin template have been removed. In variousimplementations, the centering pins need to extend about 14 mm to about15 mm into the bone to properly hold the plate in place and may extendabout 6 mm above the bone.

Some conventionally available cervical plate systems are includeopenings for centering pins, such as the anterior cervical plate systemmarketed under the tradename VENTURE™ by Medtronic Sofamor Danek USA,Inc. of Memphis Tenn. Depending upon the degree of parallelism betweenthe two centering pins, the distance between the two centering pins mayvary too much in some applications for a conventional cervical platehaving openings for centering pins to be inserted over the centeringpins. Referring to FIG. 6A, an implementation of a plate 26 thatincludes centering slots 28, 30 that provide flexibility to handledistance variations between the centering screws 32, 34. The presence ofthe centering slots 28, 30 also may provide the ability to allow forrostral and caudal adjustment of the position of the cervical platewhile the plate 26 is placed over the centering screws 32, 34. Duringsurgery, the rostral or caudal position of the plate on the vertebraemay need to be adjusted to ensure that the plate screw holes that securethe plate 26 to the vertebrae are drilled into the vertebrae withsufficient bone coverage and/or support. Because the tolerance of thecentering slots to the centering pins may be designed to be very smallin the left and right directions, the plate 26 can be moved rostrallyand caudally to a desired position without moving in the left or rightdirection and thereby losing the alignment of the plate 26 over themidline. The position of a plate 26 implementation over the vertebrae isillustrated in FIG. 6B, showing the ability of the plate 26 to moverostrally and caudally. The plate 26 also contains a window 36 at thelocation where the plate 26 meets the graft 20.

Once the plate 26 is in the desired position, the pilot screw holes forthe four screws that hold the plate 26 to the two vertebrae are drilled.Generally this is done using fixed angle drill guides which allow thesurgeon to place each screw in its own individually angled hole withinthe vertebrae. Self-tapping screws may also be utilized in specificimplementations. Relevant disclosure regarding the drilling equipmentand techniques that may be used to perform the pilot hole drilling maybe found in materials found in Appendix A to U.S. Provisional PatentApplication 61/497,528, entitled “Cervical Plate System and RelatedMethods” to Luis Tumialan which was filed on Jun. 16, 2011 (the '528provisional) which was previously incorporated by reference.

In other system implementations, centering pins may not be utilized. Inthese implementations, after the template 18 is used to drill thecentering holes 22, 24, the plate may be placed directly over thecentering holes 22, 24 and plate holding pins may be screwed throughplate holding pin holes in the plate. The plate holding pins thenphysically hold the plate in position over the midline and in positionwhile the pilot screw holes for the four plate screws are being drilled.An example of plate holding pins that could be used may be found in thedisclosure in Appendix A to the '528 provisional). This technique relieson the ability of the plate holding pins to find the centering holes 22,24 in order to maintain the position of the plate over the midline.Because this technique does not utilize centering pins, centering pindistance issues are obviated in this approach, but the ability to adjustthe position of the plate rostrally and caudally may be reducedsignificantly, depending upon whether a cervical plate like thatillustrated in the '528 provisional or a cervical plate 26 like thatillustrated in FIGS. 6A and 6B is utilized.

Referring to FIG. 7A, a third implementation of a template 38 isillustrated. As illustrated, the template 38 is sized to indicate wheretwo of the four pilot screw holes should be drilled for acorrespondingly sized plate. In this implementation of a template 38,the template 38 directly indicates the position of the pilot screw holesrather than centering holes. In this implementation, the first pilotscrew hole 40 is located on a first side of the midline and a secondpilot screw hole 42 is located on a second side of the midline. As canbe seen by inspection, the first pilot screw hole 40 is diagonallyaligned with the second pilot screw hole 42. The central hole 44 is alsolocated along the diagonal line between the first and second pilot screwholes 40, 42 (the central hole 44 is surrounded by sleeve 46 in thetemplate implementation illustrated in FIG. 7A). Because the two pilotscrew holes 40, 42 that will be drilled are diagonally aligned, as amatter of geometry, when the plate is screwed into the two pilot screwholes using the plate screws (indicated by the two screws in FIG. 7A,which would be inserted after removal of the template 38 and theplacement of a plate over the two pilot screw holes 40, 42), thelikelihood that the plate will move from the position over the midlineor rostrally or caudally may be greatly minimized while the remainingtwo pilot screw holes are drilled and the plate screws inserted.

Referring to FIG. 7B, a fourth implementation of a template 48 isillustrated. Here, the template 48 indicates the positioning of all fourpilot screw holes 50, 52, 54, 56 for a correspondingly sized plate. Whensuch a template 48 has been placed over the handle 4, it likewiseindicates the position for the pilot screw holes 50, 52, 54, 56 that maypermit the plate to be centered over the midline and help the surgeon ashas been described previously, to determine the minimum length of theplate desired. When such a template 48 is in use, the surgeon coulddrill all four pilot holes 50, 52, 54, 56 using the template 48, removethe template 48 and trial 2 and then directly screw the plate into thefour pilot screw holes (as indicated by the four screws in FIG. 7B,which would be inserted after removal of the template 48 and theplacement of a plate over the four pilot screw holes 50, 52, 54, 56),relying on the ability of the screws to find/tap the drilled holes andachieve centering of the plate over the midline location set by thetemplate 38. The surgeon could also choose to drill one of the two pairsof the diagonally opposing pilot screw holes (52, 56 or 50, 54) usingthe template 48 and screw the plate to the vertebrae prior to drillingthe remaining pair pilot screw holes. In some implementations, thesurgeon could drill the two pilot screw holes on one or the other sideof the handle 4 (or for one vertebra or the other) and screw the plateto those pilot screw holes before drilling the remaining pilot screwholes. In implementations where all four pilot screw holes are drilledprior to screwing the plate into the vertebrae, the amount of bleedingfrom the screw holes in the bone that occurs prior to the screwing on ofthe cervical plate may become an issue. Accordingly, the surgeon mayinclude the steps of packing the drilled pilot screw holes with gel foamthrombin products or bone wax while the remaining pilot screw holes arebeing drilled.

In particular implementations, a template that includes only two holescorresponding to the position of pilot screw holes on the cervical platemay include of a pair of holes that are not diagonally aligned (i.e.,ones that are on the same side of the midline). Such implementations maybe more vulnerable to loss of midline alignment of the cervical plate asthe remaining pair of pilot screw holes are drilled when the plate hasbeen screwed to the vertebrae due to rotation of the vertebrae relativeto each other during the drilling process.

In situations where two or more level surgeries are taking place,various template implementations may be created to aid in centering theplate over the midline and in determining the total length of the plateas it extends over multiple vertebrae. Referring to FIG. 8A, a firstportion 58 of a fifth implementation of a template is illustrated. Asillustrated, the first portion contains a centering hole 60 and twopilot screw holes 62, 64 and a sleeve 66 that extends around a centerhole 68. Referring to FIG. 8 B, a second portion 70 of the fifthimplementation of the template is illustrated. As illustrated, thesecond portion 70 includes a centering hole 72 and a sleeve 74 thatextends around a second center hole 76. The sleeves 66 and 72 areconfigured to fit over the handles of trials inserted between thevarious vertebrae being fused during the two or more level procedure.

In implementations of methods of cervical fusion surgery disclosedherein, in a two level surgery, the same principles disclosed aboveregarding the locating of the midpoint and use of trials to determinethe desired spacing are used. The templates utilized, however, arealtered to correspond with the different length and number of screwholes of the cervical plate utilized when fusing three or more vertebraesimultaneously. When marking the midline, the surgeon may mark themidline on all of the vertebrae, but the most important marking may beon the middle vertebra (middle body). For example, in a C 4-5, C5-6ACDF, the marking on the C5 is the most important to determining thatthe cervical plate aligns to the midpoint of the C4 and C6 vertebrae aswell. In some procedures, the first level discectomy and decompressionalong with the placing of the interbody graft can be completed withoututilizing a template. The first level could be either the rostral orcaudal to the middle body. Once the discectomy and decompression of thesecond level has been completed, a trial of the desired width is securedinto the second level.

Referring to FIG. 8C, an intermediate position during a two level ACDFsurgery is illustrated. In the example illustrated, a trial 2 has placedin the first level, which in this case is the caudal position. In thealternative, as discussed above, the trial 2 could have already beenremoved and replaced with a graft. The second portion 70 of the templatehas already been placed over the trial handle 4 and the centering hole72 has been used to drill centering hole 74 in the most caudal vertebra.Because the second portion 70 is rotatable around the handle 4 throughthe sleeve 74, the second portion 70 can then be rotated rostrally toallow the surgeon to drill a second centering hole 76 in the vertebrarostral to the most caudal vertebra. The centering hole 76 in the middlevertebra could also have been drilled using the first portion 58 of thetemplate through a similar rotation of the first portion 58 around thehandle 4 using the sleeve 66. Currently, the first portion 58 of thetemplate has been inserted over the handle 4 of the trial 2 locatedbetween the most rostral vertebra and the vertebra below it. At thispoint the surgeon is free to drill two pilot screw holes using the pilotscrew holes 62, 64 of the first portion 58, or may choose to drill athird centering hole using the centering hole 60. If the surgeon choosesto drill pilot screw holes, the plate can be secured over the midline ofthe three vertebrae, and the surgeon can then use the centering hole 74,second centering hole 76, and third centering hole (if drilled) andcentering pins or plate holding pin to hold the plate in place while theremaining pilot screw holes are drilled prior to final fixation of theplate using plate screws. In the alternative, if the surgeon chose notto drill the pilot screw holes into the middle vertebra, the thirdcentering hole would be drilled and the plate secured either withcentering pins or plate holding pins while the pilot screw holes aredrilled. Either method permits the plate to be secured to the midlineposition prior to drilling of any or the rest of the pilot screw holes.

The previous discussion involving the two implementations ofplate/centering pin templates has involved the steps involved withaligning the plate with the midline. As an aid in determining the lengthof the plate, a third portion of the template may be included inparticular implementations. Implementations of a third portion of thetemplate may be similar in appearance to the second portion 70 exceptthat they may have a portion that extends rostrally and caudally fromaround the central hole and has a total length in the rostral and caudaldirection that corresponds with the length of various plateimplementations. The third portion may also include other dimensionsthat correspond with the dimensions of various plate implementations. Inimplementations, the third portion may also include in its superior andinferior ends, centering holes (analogously to the centering hole 72included in the second portion 70). When placed over the trial handle,the third portion may be used, along with lateral fluoroscopic imaging,to determine the needed length of the plate. In addition, the thirdtemplate may be used to drill centering holes in the rostral and caudalvertebrae on either side of the middle body.

As can be observed from the previous discussion, the first portion 58,second portion 70, and the third portion of the template could beemployed in a number of different sequences and combinations during atwo or more level spinal fusion surgery, which can be readilyappreciated by those of ordinary skill in the art from the principlesdisclosed herein. In particular implementations, maintaining simplicityof the structures and techniques involved when performing a two or morelevel spinal fusion while still securing a midline position for theplate leads to use of a template that permits the surgeon to place twopilot screw holes on each side of the midline on the uppermost vertebraor the lowest vertebra.

A wide variety of sizes for first portion 58, second portion 70, andthird portions of the template are possible. For the exemplary purposesof this disclosure, third portion implementations may range from about32.5 mm to about 42.5 mm in length, first portion implementations mayrange from about 16 mm to about 21 mm in length, and second portionimplementations may range from about 16.5 to about 21.5 mm in length.

The previous discussion discloses the use of various templateimplementations for drilling of centering holes or pilot screw holeswhere the template is inserted over the handle of the trial 2. The useof grafts has also been disclosed, and the self-centering behavior ofthe graft has also been noted. Cadaver allografts are utilized invarious spinal fusion surgery methods. In other methods, the graft maybe made of polyetheretherketone (PEEK), and may include a center holelocated at the midpoint of the side of the graft that faces the cervicalplate. The center hole is generally present to allow an inserter toengage with the graft to aid in placing the graft between the twovertebrae. As a result of the natural (or physician assisted) centeringof the graft after being placed, the center hole may becomesubstantially aligned with the midpoint of both vertebrae since thegraft is likewise aligned.

Referring to FIG. 9A, an implementation of a graft 78 is illustrated ina exploded view along with an implementation of an inserter 80 and asixth implementation of a template 82. In various procedureimplementations, following placement of the trial, the graft 78 is theninserted using the inserter 80, which screws into the center hole 84 ofthe graft 78 using threads 86 on the inserter 80. The template 82 canthen be placed over the inserter 80, which is still securely fastened tothe graft 78 via the threads 84 (see FIG. 9B). In an alternativeimplementation, the inserter 80 may be removed and replaced with anotherrod with a similarly threaded end, and the template 82 placed over therod. Similarly to other template implementations disclosed in thisdocument, the template 82 contains centering holes 88, 90 for use indrilling centering screw holes. Once the centering pin template is inplace, the centering screw holes can be drilled, followed by removal ofthe template and inserter/rod from the center hole of the graft. Platecentering pins or plate holding pins can then be inserted into the boneand used to align and maintain the position of the plate over themidline or secure the plate position over the midline while the pilotscrew holes are being drilled.

A wide variety of different template shapes, including those alreadydisclosed therein may be utilized in implementations where the templateis coupled to the graft rather than to the trial. Referring to FIG. 10,a seventh implementation of a template 92 is illustrated coupled to agraft 78 through inserter 80. As illustrated, the template 92 can beattached to the graft 78 through being placed over the graft 78 once theinserter 80 has been removed and then secured to the graft as theinserter 80 is screwed back into the graft 78, allowing the template 92to couple with the threads 94 of the inserter 80. The template 92 mayalso couple over the inserter through a sleeve or central hole as hasbeen described previously. The template 92 illustrated in FIG. 10functions similarly to the similar template 38 in FIG. 7A and maysimilarly allow the template 92 to accommodate the fixed angle and/orvariable angle drill guides while also ensuring that the pilot screwholes are placed to ensure that the plate is aligned over the midlinewhen secured using the plate screws. While the plate templateillustrated in FIGS. 3 and 4 has two openings 96, 98 for two pilot screwholes, other implementations may include additional screw holes, up tothe number of pilot screw holes in the plate (for example, the four holetemplate 48 previously disclosed).

In other implementations of cervical spinal surgical systems, the systemmay not employ a template, but may operate by directly securing theplate to the graft itself through the inserter or rod. Becauseimplementations of various plates may not contain a window or otheropening internal to the plate, particularly those that are relativelyshort, some plates may be modified to include at least a small circularopening sized to allow the inserter to pass through it locatedsubstantially near the plate center to be used in these system andmethod implementations. Other implementations of plates already containa window opening in the center region of the plate of varying size andorientation relative to the center of the plate (see window 36 in plate26 in FIG. 6B for an example).

Referring to FIG. 11, a plate 100 is illustrated coupled to the graft78. In a first implementation, the coupling takes place by placing theplate 100 over the graft 78, aligning the hole 102 in the plate 100 withthe center hole 84 of the graft 78, inserting a rod 104 (which may be aninserter in particular implementations) through the hole 102 in theplate 100 and securing the rod 104 within the center hole 84 of thegraft 78. A coupling member 106 (shown here in see through) is thenplaced over the rod 104 until a threaded portion of an opening in thecoupling member 106 engages with exposed threads 108 on the rod 104 thatextend above the surface of the plate 100. By rotating the couplingmember 106 down the threads 108, the coupling member 106 simultaneouslycompresses the plate 100 against the graft 78 and secures the couplingmember 106 to the graft 78. At this point, the plate 100 is securedagainst the graft 78 and a variable or fixed angled drill guide may beused to drill the four pilot screw holes prior to the plate beingsecured to the bone through insertion of the screws.

In a second implementation of the system, the rod 104 remains fixed inthe center hole 84 of the graft 78 (or the rod 104 is first screwed intothe center hole 84), the plate 100 is inserted over the inserter/rod104, and the coupling member 106 is placed over the rod 104 and securedover the plate 100 to the graft 78 with the exposed threads 108. In yetanother variation, the plate 100 and coupling member 106 are placed overthe graft 78 and the openings in each aligned with the center hole 84 ofthe graft 78. The rod 104 is then inserted into the coupling member 106and rotated to allow the threads of the rod 104 to pass through thecoupling member 106, the plate 100 and into the center hole 84 of thegraft 78. The coupling member 106 may then be rotated slightly to ensurethat the plate 100 is securely held against the graft 78.

For implementations of plates that include windows with a rectangular orsquare dimension, depending upon whether the window is actually locatedover the plate center or not and depending upon what the desiredposition of the plate rostrally and caudally is to ensure the bestlocations for the screws to obtain purchase in the bone, the ability tomove the plate rostrally and caudally when coupled to the graft througha coupling member implantation may be advantageous. Referring to FIG.12, an implementation of a window adaptor 110 that may be used inconjunction with the coupling member 106 previously described orindependently is illustrated. As illustrated, the window adaptor 110includes two side blocks 112, 114 that each have a dovetailed recess116, 118 in a side of each of the two side blocks 112, 114. The two sideblocks 112, 114 are coupled together through a center piece 120 thatcontains two projections 122 extending from opposing faces of the centerpiece 120 that each correspond with a respective one of the dovetailedrecesses 122, 118 in the two side blocks 112, 114 (or a dovetail jointin each of the two side blocks). The center piece 120 also contains anopening 124 therethrough that is aligned substantially perpendicularlywith the dovetailed recesses in the two side blocks (dovetail joints).The opening 124 is adapted to allow the rod 104 to pass through it, andmay be threaded.

In use, the window adapter 110 is placed over the inserter/rod 104either before or after the plate 100 has been placed against the graft78. Depending upon the position of the screw openings in the plate 100against the rostral and caudal vertebrae, the position of the plate 100against the vertebrae may be adjusted rostrally and caudally by slidingthe two side blocks 112, 114 relative to the center piece 120 using thedovetailed recesses 116, 118 while the two side blocks 112, 114 areengaged with the edges of the window opening (see the implementationillustrated in FIG. 13, where a window adapter 110 is coupled to theplate 100 over the window (not shown as it is under the window adapter110)). In implementations where the coupling member 106 is used inaddition to the window adapter 110, once the plate 100 is in the desiredrostral/caudal location, the coupling member 106 may be used to tightenthe window adapter 110 against the graft 78 and tighten the plate 100against the graft 78 to hold it in the desired position. In otherimplementations where the window adaptor 106 itself acts as a thecoupling member, an additional fastener such as a nut may be used inconjunction with the threads 108 on the rod/inserter 104 to tighten thetwo side blocks 112, 114 of the window adapter 110 against the plate100. In these implementations, the two side blocks 112, 114 may overlapthe edges of the window in the plate 100 and may contain groovessubstantially equal to the thickness of the plate on each side of eachside block that face the plate 100 to allow the center piece 120 to restagainst the face of the graft through the window in the plate 100 whileaccommodating for the thickness of the plate 100. In implementationswhere window adapters 110 are used, the distance along the end of therod/inserter 104 that contains threads 108 may be extended toaccommodate the full distance from the center hole of the graft to theouter edge of the adapter. Two thread sizes and/or rotations may beemployed to allow the rod 104 to tighten into the graft 78 and allow thewindow adaptor 110 or coupling member 106 to tighten down over the rod104.

In implementations of cervical spinal surgical systems disclosed hereinthat involve securing the plate directly to the graft, the positioningof the plate along the midline may be controlled due to theself-centering behavior of the graft. However, because the plate may beable to rotate slightly around the rod during the process of drillingthe pilot screw holes, the orthogonality of the plate with the midlinemay be more difficult to control even though the plate is held againstthe graft through the coupling member. Various window adaptor designsmay allow for better cleaning and sterilization capability due to theability of the side blocks and the center piece to be fully separatedfrom each other.

Referring to FIG. 14, an implementation of a graft 126 is illustratedinserted between two vertebrae, which have had the rostral and caudalareas immediately next to the graft flattened to aid in attaching theplate. As illustrated, the graft includes center hole 128 and twotemplate openings 130 in the graft. Referring to FIGS. 15A and 15B, thetemplate openings 130 are configured to allow two prongs 134 to coupleinto them where the two prongs 134 extend from an end 136 of an eighthimplementation of a template 132. As illustrated, the template 132includes a view opening 138 in a sleeve 140 attached to the end 136,which contains one or more pilot screw holes 141 therethrough (which arelocated on winged portions on the end 136). View opening 138 is aportion of the sleeve 140 that is not present or has been removed topermit the surgeon to see what has been inserted into the sleeve 140.During use, the template 132 may be coupled to the graft 126 through thetemplate openings 130 and the two prongs 134. As can be observed in FIG.16A, the view opening 138 permits the surgeon to see the center hole 128of the graft 126. Referring to FIG. 16B, an inserter 142 with an endcontaining a flange 144 sized to engage with an end of the sleeve 140(or rod different from the inserter that originally inserted the graft126 into position) is inserted into the sleeve 140 and engaged with thecenter hole 128. Referring to FIG. 16C, As the inserter 142 is screwedinto the center hole 128 of the graft 126, the flange 144 engages withand presses the sleeve 140 and the end 136 of the template 132 againstthe graft 126. Once the inserter 142 has been fully screwed into thegraft 126, the template 132 is held against the graft 126. The twoprongs 134 are resting in the template openings 130 and work to preventany rotation of the template 132 while the pilot screw holes 141 arebeing used during the pilot screw hole drilling process.

The same principles disclosed above in the discussion of FIGS. 14-16Cmay be employed for trials where the trial handle is capable of beingremoved and reinserted after placement of the trial. In theseimplementations, an identical template design to that illustrated in theabove figures may be used and an identically designed trial handle witha flange may be employed to secure the template in an identical mannerto the trial. In these implementations, the pilot screw holes would bealigned diagonally as in the implementation illustrated in FIGS. 14-16C.

Other implementations are possible as well that involve trials that haveremovable and reinsertable handles. FIG. 24 illustrates animplementation of a template 168 that can be employed with a trial 164that has a removable handle 166. In this implementations, the template168 is configured to be held against the trial 164 through the flange onthe end of the removable handle 166. In this implementation, thetemplate 168 includes two winged portions 170, 172 at the end of thetemplate 168 and prongs similar to the design illustrated in FIG. 15B.The two winged portions 170, 172 are located on either side of themidline location in a mirrored configuration over the same vertebrawhich create an opening 174 between them that can allow the surgeon tosee the mark tattooed to the surface of the vertebra over the midline.This opening can be used by the surgeon to double check the midlineposition of the template and the trial 164 as the surgery is proceeding.Once the template 168 has been secured to the trial 164 after theremovable handle 166 has been inserted through the sleeved template andthe flange of the handle 166 has been tightened against the sleeve, thesurgeon can then drill pilot screw holes using the pilot screw holes176, 178 located through the two winged portions 170, 172 of thetemplate 168. Implementations like those illustrated in FIG. 24 may beuseful when doing multi-level spinal fusions, as they allow the surgeonto use the template 168 to establish the midline position of the plateto be set on either the uppermost or lowest vertebra by drilling justtwo holes initially In various implementations, the use of the two holesmay simultaneously secure both the midline position and ensureorthogonality of the plate based on the principles disclosed in thisdocument.

Several implementations of various interbody grafts and trials have beendisclosed in this document. Additional implementations of grafts andtrials disclosed in the following section may also be used with any ofthe cervical spinal surgical systems disclosed herein.

The average distance from the uncal vertebral joint on one side of avertebra to the uncal vertebral joint on the other side ranges fromabout 15 mm to about 16 mm at C4-5 to about 17 mm to about 18 mm at C5-6and C6-7. The total distance from joint to joint ranges from about 17 mmto about 18 mm at C4-5 to about 20 mm to about 21 mm at C5-6 and C6-7. Asubtle flattening of the uncal joint slope also exists as one proceedscaudally in the subaxial spine. Because these measurements areremarkably constant when compared between men and women of differentheights, implementations of trials and interbody grafts that correspondto these measurements and incorporate slopes on two edges that correlatewith the slope of the uncal joints of a specific cervical vertebra pairmay be constructed. The measurements and an example of a trial 146comprising a handle 148 that includes two opposing edges 150, 152 thatincorporate a slope that correlate with or correspond with the slope ofthe uncal vertebral joint is illustrated in FIG. 17.

Interbody grafts of all types may also be modified to incorporatesimilarly sloped opposing edges that correlate with or correspond to theslope of the uncal vertebral joint. Because of the presence of thesloped opposing edges, the graft may be enabled to be moreself-centering than before (and similarly, a trial with similarly slopedopposing edges will exhibit similar self-aligning behavior). Inparticular implementations, grafts that are PEEK interbody devices likethose disclosed herein may be modified in a similar fashion toincorporate these rounded structures. An example of such animplementation of a graft 154 is illustrated in FIG. 18.

In the implementation illustrated in FIG. 18, the rounding of the twoopposing edges 156, 158 may occur about 2 mm from each side of thegraft. The distance between the two opposing edges 156, 158 where therounding begins is about 12 mm in this implementation. Because theproportions of the uncal vertebral joints and the spacing between themis consistent across both men and women, the measurements described forthe graft 154 illustrated in FIG. 18 may work for the vast majority ofpatients. However, other graft sizes for specific situations may also beselected to accommodate specific cases. The principles disclosed in thisdocument may also be used to perform similar modifications to corticalcancellous grafts.

Use of the modified graft implementations disclosed herein may alsoallow for optimization of the bone-graft interface by permitting alarger portion of the surface of the graft facing the vertebrae tocontact the vertebral surfaces. Because the two opposing edges 156, 158of the graft 154 are sloped, the graft 154 is capable of achievingcloser proximity to a vertebral surface caudal to it that is roundedthan if the graft 154 had sharp square edges which hold the graft 154away from the vertebral surface beneath it. The presence of a gapbetween the surfaces of the graft and the vertebral surface poses achallenge to the fusion process and creates risk that the fusion willnot take place as successfully and/or that recovery time will beprolonged.

As has been discussed, cervical spinal surgical systems like thosedisclosed herein may be utilized to ensure that the alignment of theplate is orthogonal and aligned with the midline of the vertebraeinvolved in a fusion surgery as well as ensuring that a plate that isnot longer than necessary is used to make the fusion possible.Conventional surgical techniques present midline alignment issues causedby movement of the plate caused during drilling of the pilot screwholes. When the plate has moved from being directly over the midline, alonger plate is likely to be required. Also, as was previouslymentioned, due to the presence of the uncal vertebral joints, the graftsnaturally tend to self-center, as do the the trials during surgery.Because interbody grafts do not have a coronal tilt, aligning the plateusing the trial which corresponds with the ultimate alignment of theinterbody graft may geometrically ensure an orthogonal plate.

That this tendency for the graft to self-center exists even when theplat is not orthogonal can bee see in FIG. 19 (a CT reconstruction)where the graft 160 is lying within the relative center of the uncaljoint while the white dots 162 indicate the position of the screws ofthe plate, which can be seen is tilted to the right significantly.

FIGS. 20-22 illustrate sequential lateral intraoperative fluoroscopicimages of a plate placed after the midline was previously visuallyidentified and plate holding pins predrilled. FIG. 20 illustrates thefirst plate holding pin screwed in place and FIG. 21 illustrates thesecond plate holding pin screwed in place. A fixed angle drill guide wasthen used to drill holes into the vertebral bodies with the plateimmobilized by the plate holding pins. A plate screw inserted into thecaudal vertebral body can be seen in the image of FIG. 22. FIG. 23 is apost-operative AP x-ray indicating midline placement of the cervicalplate without the use of any AP fluoroscopic imaging during surgery tocontrol the need to identify the midline position of the plate underplate limiting visualization conditions once the plate was placed overthe graft. These images demonstrate proof of the concept that the use ofpredrilled holes following identification of the midline and plateholding pins can maintain the plate in midline position through theprocess of drilling of the pilot screw holes and can result in midlineplacement of the plate.

Implementations of templates, plates, inserters, grafts, and otherimplementing components may be made of any of a wide variety ofconventional and other materials, including by non-limiting example,metals, plastics, composites, biologics, ceramics, and the like.

In places where the description above refers to particularimplementations of cervical spinal surgical systems, it should bereadily apparent that a number of modifications may be made withoutdeparting from the spirit thereof and that these implementations may beapplied to other cervical spinal surgical systems.

What is claimed is:
 1. A device for use in a cervical spinal operationcomprising: a trial comprising a handle removably coupled to the trialat a back face of the trial opposing a substantially flat front face;wherein the trial is configured to be inserted between two cervicalvertebrae; wherein two opposing edges of the trial each include a slopecorresponding with a slope of a concave portion of an uncal vertebraljoint of a cervical vertebra when the trial is inserted between twocervical vertebrae; wherein the trial comprises a flat surfaceconfigured to face a portion of the uncal vertebral joint opposite theconcave portion of the uncal vertebral joint when the trial is insertedbetween two cervical vertebrae; and wherein the flat surface extends anentire width of the trial perpendicular to a length of the handlecoupled to the trial.
 2. The device of claim 1, wherein the trial isconfigured to automatically center the handle over a midline position oftwo vertebrae through the slope included in each of the two opposingedges of the trial.
 3. A trial for use in a cervical spinal operationcomprising: a block comprising a first end, a second end, a first face,and a second face, wherein the first end opposes the second end and thefirst face opposes the second face; and a handle removably coupled tothe first end of the block; wherein a surface of the first end of theblock is substantially parallel to a surface of the second end of theblock; wherein the first face comprises a flat surface configured toface a portion of an uncal vertebral joint opposite a concave portion ofthe uncal vertebral joint when the trial is inserted between twocervical vertebrae; wherein the flat surface extends an entire width ofthe trial perpendicular to a length of the handle coupled to the trial;wherein the second face comprises a curved surface; wherein the curvedsurface corresponds with a slope of the concave portion of the uncalvertebral joint when the trial is inserted between two cervicalvertebra; wherein the first face and the second face are configured tofit between two cervical vertebrae; and wherein a width of the firstface perpendicular to a distance between the first end and second end isthe same as a width of the second face perpendicular to the distancebetween the first end and second end.
 4. The device of claim 3, whereinthe trial is configured to automatically center the handle over amidline position of two vertebrae through the second face.
 5. The deviceof claim 3, wherein the handle is configured to screw into the first endof the block.
 6. The device of claim 3, wherein an outer perimeter ofthe second end is substantially a hexagon, wherein a first side of thehexagon and the second side of the hexagon are each curved.